1. Field of the Invention
The present invention relates generally to electronic devices, and more particularly, to a power supply for an electronic device.
2. Related Art
Hearing impairment, which may be due to many different causes, is generally of two types, conductive or sensorineural. In some cases, a person may have hearing loss of both types. Conductive hearing loss occurs when the normal mechanical pathways for sound to reach the hair cells in the cochlea are impeded, for example, by damage to the ossicles. Conductive hearing loss is often addressed with conventional hearing aids which amplify sound so that acoustic information can reach the cochlea.
In many people who are profoundly deaf, however, the reason for their deafness is sensorineural hearing loss. This type of hearing loss is due to the absence or destruction of the hair cells in the cochlea which transduce acoustic signals into nerve impulses. Those suffering from sensorineural hearing loss are thus unable to derive suitable benefit from conventional hearing aids due to the damage to or absence of these mechanisms for naturally generating nerve impulses from sound.
It is for this purpose that one type of auditory prosthesis, a cochlear implant (also commonly referred to as cochlear prosthesis, cochlear device, cochlear implant device, cochlear implant system and the like; generally and collectively sometimes referred to herein as a “cochlear implant”) has been developed. As described in more detail below, a cochlear implant often includes an external component coupled to an internal component via a transcutaneous link. The internal component typically includes an array of stimulation electrodes implanted in the cochlea of the patient (referred to herein as a recipient). The electrode array is controlled by an electronic system encased in a hermetically sealed, biocompatible housing typically implanted in the mastoid. The electronic system, commonly referred to as a stimulator unit, essentially contains decoder and driver circuits for the stimulation electrodes. Acoustic sound reception and conversion of acoustic signals into electrical signals typically occurs in a speech processor. The speech processor may be worn by the recipient or may be implanted in the recipient. A microphone is typically located outside of the recipient's body, and may sometimes be positioned in a behind-the-ear housing worn on the auricle. Cochlear implants bypass the hair cells in the cochlea by directly delivering electrical stimulation to the auditory nerve fibers via the implanted electrode array. This enables the brain to perceive a hearing sensation resembling the natural hearing sensation normally delivered to the auditory nerve.
Like other electrically powered devices (simply electronic devices herein), components of a cochlear implant require a certain necessary amount of power so as to perform various operations. This necessary amount of power is typically supplied by a power supply comprising one or more battery cells. The power supply is integrated with, or electrically coupled to, the cochlear implant.
The amount of power necessary for proper operation may vary considerably from user to user, and from operation to operation. Furthermore, the amount of power required by components of the implant may depend on, for example, the stimulation rate employed by the implant to stimulate the cochlea, the speech processing strategy employed to convert a received sound to an electrical signal, etc. As would be appreciated, higher stimulation rates and more complicated speech processing strategies require larger amounts of power.
Similarly, the power requirements are also strongly influenced by recipient characteristics, such as the thickness of the skin separating the elements of the external and internal components that comprise the transcutaneous link. Larger skin flaps require larger amounts of power to transmit information and power there through.
As such, a power supply employed in a cochlear implant should be designed to supply various amounts of power so that the power supply does not need to be customized based on recipient characteristics, or on the device capabilities. However, with the introduction of new technologies, the size of cochlear implants, and particularly the size of the external components, is rapidly being reduced. These reduced sizes lead to restrictions in the type, size and dimension of the power supplies which may be utilized in cochlear implants.